The proposed research will help characterize excitatory neurotransmission within the olfactory bulb (OB) and improve understanding of olfactory physiology. AMPA/kainate (A/K) receptors play an important role at excitatory synapses in the OB, but the relative contribution of AMPA receptors vs. kainate receptors is unknown. The expression, distribution, and functional properties of A/K receptors in the mammalian OB remain largely undefined due to past limitations in the specificity of antibodies and ligands for receptor subtypes. As specific receptor subtypes have distinct functional properties and can regulate important aspects of neuronal circuit function (e.g., synaptic integration, and transmitter release), this knowledge is necessary for understanding OB function. One goal of these experiments is to determine the synaptic distribution of specific AMPA and kainate receptor subunits using immunofluorescent double-labeling with synaptophysin. Another goal is to use whole-cell recording techniques, in conjunction with recently available selective receptor agonist and antagonists, to determine the relative contributions of A/K receptors to pre- and postsynaptic components of transmission. The information gained from these experiments will help clarify the distribution, biophysics, and modulation of A/K receptors as well as their role in excitatory neurotransmission, svnaptic timing, and odor-information processing.